Same issue, both mine faulty after 40 days. Got anywhere with them? Store confused about 21 day return policy and warranty return. Spoke to warranty, they only have facility to return chargers in box with device. Spent endless hours like you and got nowhere.
Just a heads up, if a manufacturer such as Samsung is selling goods directly in the UK, they MUST uphold the terms of the sales of goods act. They cannot overrule it.
It's different if you order them from outside of the company and have them shipped in.
There is no policy or contract that can, regardless of wording deny you statutory rights. Any that do are by definition illegal.
Also any refurbished items that may be provided under said manufacturers warranty come with an obligatory further 6 months, from date of receipt warranty.
So if after 11 months, you get a refurbished replacement, your warranty now extends past the 12 months. This is also unavoidable and can run indefinitely should further replacements be issued during any of these extended periods, but manufacturers will rarely make people aware, least of all their customer service reps.